1. Technical Field
The present invention relates to a liquid ejecting head such as an ink jet type recording head, and particularly relates to a liquid ejecting head including a wiring member.
2. Related Art
A liquid ejecting apparatus is an apparatus that includes a liquid ejecting head which can eject a liquid through a nozzle as a liquid droplet and that ejects various liquids through the liquid ejecting head. For example, a representative liquid ejecting apparatus can include an image recording apparatus such as an ink jet type recording apparatus that includes an ink jet type recording head (hereinafter, referred to as a recording head) and performs recording by ejecting a liquefied ink through a nozzle of the recording head as an ink droplet. In addition to this purpose, the liquid ejecting apparatus is used in ejecting various types of liquid such as color materials used in color filters for a liquid crystal display, organic materials used in an organic electro luminescence (EL) display, and electrode materials used in forming electrodes. Then, the recording head for the image recording apparatus ejects the liquefied ink, and a color material ejecting head for a display manufacturing apparatus ejects each solution of red (R), green (G), and blue (B) color materials. In addition, an electrode material ejecting head for an electrode forming apparatus ejects liquefied electrode materials, and a bio-organic material ejecting head for a chip manufacturing apparatus ejects a bio-organic material solution.
The recording head as described above is configured so that the ink droplet is ejected through the nozzle communicating with a pressure chamber by deforming a piezoelectric element (a type of pressure generating element) bonded to a diaphragm to generate pressure fluctuations in the ink inside the pressure chamber. The piezoelectric element has a piezoelectric layer interposed between a common electrode which is common to a plurality of piezoelectric elements and an individual electrode which is individually patterned for the respective piezoelectric elements. In addition, a wiring terminal of a flexible cable is configured to be electrically connected to an electrode terminal of the common electrode and the individual electrode (for example, refer to JP-A-2011-167964). The flexible cable is a film-like wiring member on which an IC for driving the piezoelectric element, such as a chip on film (COF) and a tape career package (TCP) is mounted. Here, each electrode terminal and each wiring terminal corresponding thereto are bonded to each other by an adhesive such as a non-conductive paste (NCP), a non-conductive film (NCF), an anisotropic conductive paste (ACP), and an anisotropic conductive film (ACF). Then, the recording head supplies (applies) a drive voltage to both electrodes of the piezoelectric element via the flexible cable, thereby deforming the piezoelectric layer and ejecting the ink droplet through the nozzle.
Incidentally, in the related art, in order to reduce electrical resistance between the electrode terminal of the common electrode and the wiring terminal corresponding thereto, as illustrated in FIG. 8A, a terminal 81′ which is a conductive portion of a wiring terminal 80′ is increased as much as possible, and a region electrically connected to an electrode terminal 82′ is sufficiently secured. However, in this configuration, a portion other than the terminal 81′ in the wiring terminal 80′ of a flexible cable 84′ is decreased. Consequently, a bonding force between the electrode terminal 82′ and the wiring terminal 80′ is weakened. In particular, when the electrode terminal 82′ and the wiring terminal 80′ are bonded to each other by using a non-conductive adhesive 83′ such as the NCP or the NCF, the terminal 81′ of the wiring terminal 80′ and the electrode terminal 82′ are brought into contact with each other, and are bonded to each other by the adhesive 83′ filling a portion between both terminals 80′ and 82′ other than a contact portion thereof. Consequently, if a gap into which the adhesive 83′ flows is small, the bonding force is significantly weakened. In addition, when gold or platinum is used as a material for the terminal 81′ of the wiring terminal 80′ or the electrode terminal 82′, there is a possibility that an adhesive force by means of the adhesive 83′ may be further weakened.
In order to prevent the above-described weakening of the bonding force (adhesive force), as illustrated in FIG. 8B, a configuration is proposed where multiple electrode terminals 82″ are divided so as to be arranged by being spaced apart from one another in a bonding region to which the electrode terminal 82″ and a wiring terminal 80″ are bonded, and multiple terminals 81″ of a wiring terminal 80″ of a flexible cable 84″ are similarly arranged corresponding to the electrode terminals 82″. If configured in this way, an adhesive 83″ can fill a gap generated in contact portions between the terminal 81″ of these wiring terminals 80″ and the electrode terminal 82″. Accordingly, it is possible to strengthen the bonding force between the electrode terminal 82″ and the wiring terminal 80″. However, in this configuration, if a bonding position is misaligned between the electrode terminal 82″ and the wiring terminal 80″ as illustrated in FIG. 8B, there is a possibility that an area cannot be sufficiently secured in a region where the terminal 81″ of the wiring terminal 80″ and the electrode terminal 82″ are electrically connected to each other. Therefore, there is a possibility of increasing electrical resistance between both terminals 80″ and 82″.